At STP a 7.49-gram sample of an element has a volume of 1.65 cubic centimeters. What is the element?

1 Answer
Ernest Z.
Dec 14, 2016

The element is titanium, #"Ti"#.

Explanation:

The density (#ρ#) of anything is its mass (#m#) divided by its volume (#V#).

#color(blue)(bar(ul(|color(white)(a/a)ρ = m/Vcolor(white)(a/a)|)))" "#

In this problem,

#m = "7.49 g"#
#V = "1.65 cm"^3#

∴ #ρ = m/V = "7.49 g"/("1.65 cm"^3) = "4.54 g/cm"^3#

We consult a list of chemical elements sorted by density.

#ρ"/g·cm"^"-3"color(white)(m)"Element"color(white)(m)"Symbol"color(white)(m)"At. No."#
#stackrel(—————————————————)(color(white)(m)4.47color(white)(mm)"Yttrium"color(white)(mmll)"Y"color(white)(mmmm)39)#
#color(white)(m)4.54color(white)(mm)"Titanium"color(white)(mm)"Ti"color(white)(mmmll)22#
#color(white)(m)4.79color(white)(mm)"Selenium"color(white)(mml)"Se"color(white)(mmmll)34#

The three most likely elements are #"Y, Ti"#, and #"Se"#.

The element is probably titanium, #"Ti"#.

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